Heretofore, hand operated tools have been provided for use in welding a stud to a workpiece, but an obvious disadvantage of using such tools is the difficulty to insure accurate positioning of a stud where close tolerances are required.
Various numerically controlled welding machines are also available, which provide for accurately controlled positioning of studs. However, machines of this type are normally quite expensive and on this basis not suitable for use in relatively small manufacturing operations or shops.
A simple and relatively inexpensive technique presently in use for achieving accurate positioning of studs involves the use of a template accurately bored to define properly located guide openings for use in controlling the positioning of a stud welding electrode relative to a workpiece. With this technique, it is necessary to glue a non-electrically conductive guide bushing or ring within each of the guide openings to electrically isolate the electrode from the template, during relative movement of the electrode and workpiece between remote stud loading and adjacent stud welding positions. Thus, a drawback of this technique is that wearing away of the guide bushings or rings, occurring as a result of sliding surface engagement thereof with the electrode, eventually introduces inaccuracies in positioning of the studs, where a number of like workpieces are required to be fabricated. A further drawback of practicing this technique is that presently available welding apparatus used therewith, and of which I am aware, employs the force of gravity to retain a stud to be welded in association with the welding electrode. Thus, the workpiece and template must be positioned above the electrode in an inverted condition, such that it is difficult to visually align the guide bushings with the electrode prior to each stud welding operation. An additional drawback involves the thickness of the template and bushing required to provide for proper guiding of the electrode; such thickness being necessarily greater than the axial length of the head end portion of the stud projecting beyond the end of the electrode to provide for guiding of the electrode before such head end bottoms out against the workpiece.